Answer:
(6/7)/(12/21) = 4/x
the first part of the expression :
when divide fraction: turn the sign from ÷ to × and flip the second fraction
(6/7)×(21/12)=4/x
126/84=4/x ( simplify the fraction 126/84)
GCF of 126 and 84 is 42 ( 126/48=3 and 84/42=2)
3/2=4/x ( cross multiplication ( butterfly)
1.5=4/x
1.5x=4
x=4/1.5=2.6666.......
